The M20F Performance Benchmark thread.

[Ragsf15e]

2 hours ago, Vance Harral said:

I'm sure you're not, but either your instrumentation or your engine or your baffling is amiss somehow.  There's no way a stock M20F departing from a Colorado airport should have any cylinder at 450F during a Vy climb, regardless of atmospheric conditions or where the mixture is set.  On the very warmest days in summer, our engine might be a few degrees over 400, briefly.  I've never seen anything remotely close to the factory redline of 460 in our airplane, or other E/F models I've flown in around here, for 20+ years.

I respectfully disagree and suggest you do some Colorado Springs takeoffs next summer ~85 degrees and 50-100 rop.  Let’s see what your temps look like around say 3000’ agl.  I’m curious now.

[Vance Harral]

I live in the Denver Metro area and trek down to the Springs several times a year to go to the Airplane Restaurant for $100 hamburgers.  We download and keep our engine monitor data, so I've got plenty of info on this.

I went back 3 years and tried to find the absolute hottest day on which I  or one of my partners had a recorded flight, correlating temps from https://www.wunderground.com/.  The plot below is from July 11, 2023, when the high at KBJC (elevation 5673') was 95 degrees F.  It's a long flight, and while we didn't have altitude recording at the time, it's essentially guaranteed by the length of the flight that the climb out was to 3000' AGL or higher.  I'm not claiming the flight departed at the hottest point of the day, but it was obviously hot all day long.  Hottest CHT in the initial climb peaks at 389F before quickly settling down at level-off.  A later climb at higher altitude gets right to 400, again before quickly settling down.

I also pulled the raw data from the CSV files over the past two years and sorted it.  The highest CHT we've ever recorded on any day under any conditions in those two years is 413F.

We've had all-cylinder CHT monitoring since 2006, and in all that time I've never seen anything remotely approaching 450.  If you're confident your instrumentation is good and all your baffling is pristine, then the only thing I can think of is you're developing more power than stock, and/or your cylinders run hot (are they chrome perchance?)